不但
他不但会说中文，而且会写汉字。
He can not only speak Chinese, but also write Chinese characters.
Used to indicate that something is true in the first clause, and adds that another thing is also true in the second clause.
这道菜不但好看，而且好吃。
This dish is not only good-looking, but also delicious.
她不但聪明，而且勤奋。
She is not only smart, but also diligent.
Often paired with '而且' (érqiě, 'but also') or '还' (hái, 'also') in the second clause to emphasize the additional point.
Pro Tip
Pair with '而且' or '还'
To sound natural, always pair '不但' with '而且' (but also) or '还' (also) in the second clause. Example: '不但...而且...' or '不但...还...'.
Gold Rule
Avoid standalone use
Do not use '不但' alone. It must be followed by another clause that provides additional information.
Word Origin
Composed of '不' (bù, 'not') and '但' (dàn, 'only/but'). The phrase evolved from classical Chinese conjunctions to modern Mandarin usage.
Usage Notes
This phrase is used to connect two clauses where the second clause adds an additional point to the first. It is common in both spoken and written Chinese.